The present invention relates to a therapeutic agent for disorder in brain and nerve. More particularly, it relates to a therapeutic agent for disorder in brain and nerve containing HGF (hepatocyte growth factor) as an active ingredient.
HGF is a protein discovered by the present inventor in the serum of rats with a regenerating liver as a factor inducing proliferation of mature hepatic parenchymal cells in vitro (Biochem. Biophys. Res. Commun., 122, 1450, 1984). The inventor further succeeded in isolating HGF from rat platelets (Proc. Natl. Acad. Sci., 83, 6489, 1986, FEBS Letter, 22, 311, 1987), and determined a part of its amino acid sequences. On the basis of the clarified amino acid sequences of HGF, the inventor carried out cloning of human and rat HGF cDNAs, and succeeded in obtaining the hepatic parenchymal cell growth factor as a recombinant protein using the cDNA in animal cells (human HGF: Nature, 342, 440, 1989; rat HGF: Proc. Natl. Acad. Sci., 87, 3200, 1990).
The molecular weight of HGF is 82 to 85 kD in SDS-polyacrylamide gel electrophoresis. The rat HGF molecule has a heterodimer structure of xcex1-chain composed of 463 amino acid residues and xcex2-chain composed of 233 amino acid residues, and both xcex1-chain and xcex2-chain are crosslinked to each other with one disulfide bond and have two glucosamine-type sugar chain binding sites. The human HGF also possesses almost the same physiological activity, and has xcex1-chain composed of 463 amino acid residues and xcex2-chain composed of 234 amino acid residues. The xcex1-chain has 4 kringle structures similar to that of fibrinolytic enzyme plasmin, and the amino acid sequence of xcex2-chain has about 37% homology with xcex2-chain of plasmin having serine protease activity. The homology of amino acid sequence between rat HGF and human HGF is very high, i.e. 91.6% in xcex1-chain and 88.9% in xcex2-chain, and their activities can be utterly exchangeable.
HGF discovered as a factor for specifically proliferating the hepatic parenchymal cells has been disclosed to show various activities in the body as a result of recent studies by the inventor and other researchers, and it is expected to be applied in remedies for humans and animals, as well as the subject of study.
The inventor proved that HGF acts as a growth factor not only on hepatocytes but also widely on epithelial cells, and have completed several inventions. In Japanese Patent Kokai No. 49246/1992, the inventor described the development and application of HGF as a medicine for renal diseases on the basis of the action of HGF to promote cell proliferation in proximal tubule of the kidney. On the basis of the HGF action to promote proliferation of normal epithelial cells such as melanocytes and keratinocytes, the inventor also described in Japanese Patent Application No. 419158/1990, the development and application of HGF as an epithelial cell growth accelerator for wound healing and skin ulcer treatment or as a medicine for the proliferation of hair root cells. In particular, HGF does not have carcinogenic effect and the activity of promoting the proliferation of cancer cells, which are observed with many growth factors such as EGF, and hence it is more practicable. The inventor, moreover, in Japanese Patent Kokai No. 25010/1994, described that HGF could be used as an anti-cancer agent utilizing the property of HGF to inhibit the proliferation of cancer cells such as HepG2 cell line derived from a human hepatoma, IM9 cell line derived from lymphoblast tumor and the like.
More recently, the inventor discovered that HGF promotes regeneration in injured lung, and that the plasma HGF level in patients with lung diseases is far higher than that in normal subjects (Yanagita et al., Biochem. Biophys. Res. Commun., 182, 802-809, 1992).
Relating to the receptor of the HGF, it has been identified from the recent studies that c-met proto oncogene codes the HGF receptor (Bottaro et al., Science 251, 802-804, 1991; Naldini et al., Oncogene 6, 501-504, 1991).
Another important point in considering the practical use of HGF as medicine is that HGF promotes the growth of cells only in phase G1, that is, the cells only in the growth period, not cells in phase G0, that is, stationary period. It means that it promotes growth and regeneration of injured tissues, but does not act at all on intact tissues. Therefore, if HGF is administered excessively, or if HGF reaches non-ailing sites through blood or the like, it does not induce carcinogenic action or excessive growth in normal tissues.
Since HGF widely promotes growth of epithelial cells, as well as hepatocytes, and has the growth inhibitory activity for cancer cells, it is expected that HGF acts to heal tissue injuries in the body. HGF producing cells are not epithelial cells themselves, but it is elucidated that HGF is produced mainly by mesenchymal cells, for example, Kupffer cells and vascular endothelial cells of sinusoidal wall in the liver, capillary endothelial cells in the kidney, alveolar macrophage and vascular endothelial cells in the lung, and it has been elucidated that HGF is supplied from adjacent cells when required, and the so-called paracrine mechanism is established.
However, when the liver or kidney is injured, production of HGF is increased also in intact organs such as the lung, and it is estimated that HGF is supplied also by the so-called endocrine mechanism.
Thus, the HGF is a growth factor acting to heal wounds in various organs and tissues, but in the event of disorder in brain and nerve, it has not been known whether HGF contributes to restoration of brain and nerve injuries or not. Accordingly, the inventor studied the action of HGF in the brains and nerves, and found that survival of brain and nerve cells is promoted by HGF, and that expression of HGF mRNA and c-met mRNA in the brains is evidently increased in the body having brain injury.
The invention is based on such findings, and it is hence a primary object of the invention to present a useful therapeutic agent for disorder in brain and nerve for prevention and treatment of disorder in brain and nerve.
The invention relates to a therapeutic agent for disorder in brain and nerve containing an effective amount of HGF and if necessary, a pharmacologically acceptable carrier.
Other aspects of the invention include a method of treatment of disorder in brain and nerve of humans or mammals by administering an effective amount of HGF; a use of HGF for manufacturing a therapeutic agent for disorder in brain and nerve; an agent promoting survival of brain and nerve cells containing an effective amount of HGF and if necessary, a pharmacologically acceptable carrier; a method of promoting survival of brain and nerve cells of humans or mammals by administering an effective amount of HGF; and a use of HGF for manufacturing an agent promoting a survival of brain and nerve cells of humans or mammals.
HGF as described above may be derived from either human or animal tissue or blood components, or manufactured by recombinant DNA technique.
HGF, the active ingredient, possesses an action for promoting survival of brain and nerve cells, and hence can regenerate and restore the insured brains and nerves.